Fumiyasu Utsunomiya

Adaptive-Vth CMOS/SOI DC-DC Converter Scheme for 0.3-V Operation

An adaptive-Vth CMOS/SOI DC-DC converter scheme, which consists of a low-Vth charge-pump circuit and a high-Vth DC-DC converter, and enables to operate at 0.3-V, is proposed. The low-Vth circuit starts to boost a small input voltage and generates output power. And then the high-Vth converter continues the boosting operation by using the power of the low-Vth circuit. If once the high-Vth converter starts, the low-Vth circuit automatically stops the boosting operation. We fabricated the adaptive-Vth DC-DC converter with a 0.8-mum FD-SOI process and verified the converter has a conversion efficiency of more than 80% at an input voltage of 0.3 V

Sub-1-V Power-Supply System with Variable-Stage SC-Type DC-DC Converter Scheme for Ambient Energy Sources

This paper describes a sub-1-V power-supply, which is useful for self-powered short-range wireless systems with ambient energy sources. A variable-stage DC-DC converter, which consists of multi-stage switched capacitor circuits and has intermittent operation with an external capacitor, makes it possible to extend the time for self-powered operation. We fabricated a variable-stage DC-DC converter and an intermittent operation circuit with a 0.8-μm CMOS/SOI process. We also applied the sub-1-V power-supply system to a self-powered short-range wireless system and verified its effectiveness.